Vacuum-pump.



PATBNTED MAR. l0, 1903.

J. STUMPF. VACUUM PUMP.

APPLIOATION FILED ooms. 1901.

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PATBNTUD MAR. 1o, 1903.

J. sTUMPP. VACUUM PUMP.

APPLIOATION FILED OUT. 8, 1901.

2 SHEETS-SHEET 2 I0 MODEL.

UNITED STATES PATENT EEICE.

JOHN STUMPF, OF BERLIN, GERMANY.

SPECIFICATION forming part of Letters Patent No. 722,416, dated March10, 1903.

y Application filed October 8, 1901.

To a/ZZ whom. it ntcty concern:

Be it known that I, JOHN STUHPF, a subject of the King of Prussia,German Emperor, re-

siding at Berlin, Kingdom of Irussia, German Empire, have invented a newand useful Improvement in Vacuum-Pumps, of which the following is aspecification. 1

My invention relates to an improvement in vacuum-pumps for usein'withdrawingair or gas, as from a chamber wherein it is desired tocreate or maintain a partial vacuum.

My object is to provide a-vsteam-actuated double-acting vacuum-pump ofsimple and improved construction and having relatively great workingcapacity.

In the drawings, Figure l is -a longitudinal section of a double-actingvacuum-pump of my improved construction; Fig. 2, a broken and enlargedsection through one ofthe steam slide-valves, showing the valve inexhaust position; Fig. 3, a similar view of the same valve in theposition of opening the steam-inlet port, and Fig. 4a broken andenlarged section showing one of the air or gasv outlet valves of thepump-cylinder.

A is a shell or casing, which maybe con-` structed in sections, asshown,for convenience in placing the parts inposition. 'Ihe shell Aincloses a pump-cylinder B and steam-cyl-A inders C D. Surrounding thecylinder B is a cored chamberfE, having an inlet E,'and communicatingwith the interior'of the ,cyl-A inder B through an annular series ofopenings a., located exactly midway between the cylinder-heads b c.Working in the cylinder B is a hollow piston F, and formed integraltherewith are hollow pistons F F2, working in the cylinders C D. OnY theouter ends of the cylinders O D are valve-chests C D', respectively,each provided centrally with a cylindrical valve-chamber d,communicating through an annular series of ports e with an annularsteam-inlet chamber e', receiving steam through the pipe e2, andprovided also with an annular series of exhaust-ports f, communicatingwith an annular exhaustchamber f', having an exhaust-pipe f2.' In thechambers d are cylindrical slide-valves G. Each valve G is formed with acentral enlarged part g, working in the chamber d, and reduced endportions g g2, working in guide-openings at opposite ends of thechamserii No. 78,006. (No man.)

ber d. The valve G is hollow and is provided through its enlarged part gwith a steam inlet and exhaust opening g3. The valves G are on the endsof the valve-stems G', having heads h attheir free ends and shoulders 7iadjacent to the slide-valves. In the parts F F2 of the piston device areguidetubes t', provided in their ends with guideopenings z'" for thestems G. In the guidest around the openings t are annular shoulders 712to engage the heads 7L, as hereinafter described. The hollowslide-valves contain annular chambers 7c in open communication with thecylinders C D and with the steamports g3. H H are outwardly-opening eX-haust-valves in the cylinder-heads b c. The valves Hare held to theirseats by springs Z.

The piston F is of a length slightly less than one-half the length ofthe chamber ot' the cylinder B, whereby when moved to eithercylinder-head b c it will just uncover the ports a. The pistons F F2 arepreferably of about the same length as the chambers of the cylinders CD, though they may be somewhat shorter.

In practice the inlet-opening E communicates with the chamber from whichair or gas Ais to be withdrawn, and the valves H open to the surroundingatmosphere. Any air or gas in the chamber'or the like to be exhaustedwill expand through the inlet E to the annularchamber E. In the movementor' the piston F to the position shown it has created a Vvacuum in thatpart of the cylinder B to the left of the ports a, so that when thepiston has reached the position shown any air in the chamber E willexpand into the cylinder. In the nal movement of the piston F to thecylinder-head c air in that half of the cylinder has been dischargedthrough .the respective valve H, and the engagement IOO this movement ofthe piston a vacuum is created between it and the cylinder-head c,whereby when the ports ct are uncovered the air or gas to be withdrawnwill expand into the cylinder. In the final movement of the piston ineither direction it engages the head h of the stem of one valve to openthe steaminlet and engages the stop h.' of the stem of the other valveto close the steam-inlet port and open the steam-exhaust port. Thus theactions are repeated. In spite of the difference in area between theworking faces of the piston F and the pistons F' F2 as the resistance t0movement is never greater than atmospheric pressure' the steam-pressureneed not be high. To give the pump the greatest capacity, there shouldbe no clearance between the piston F and adjacent cylinder-head when thepiston reaches the end of its stroke. The pump may be operated at anydesired speed andl may be caused to withdraw air or gas very rapidly.

While I prefer to constructmy improvements throughout substantially asshown and described, they may be variously modifiedL in the matter ofdetails of construction without departing from my invention as definedby the claims.

What I claim as new, and desire to secure by Letters Patent, is-

1. In a vacuum-pump, the combination of a pump-cylinder provided in itsends with valved outlet-ports and midway between its ends with aninlet-port, a pump-piston movable in the cylinder to the ends thereofwithout clearance and adapted at the end of its stroke in eitherdirection to uncover the inlet-port, a steam-cylinder at each end of andconcentric with the pump-cylinder, steampistons connected with thepump-piston and movable in the steam-cylinders, and steamvalves at thesteam-cylinders movable to admit and exhaust the steam alternately atthe steam-cylinders, said valves being controlled by the movement of thepistons.

2. In a vacuum-pump, the combination of a pump-cylinder provided in itsends with valved outlet-ports and midway between its ends with anannular series of openings forming the inlet-port, an inlet-chambercommunicating with the series of openings, a pumppiston movable in thecylinder to the ends thereof without clearance and adapted at the end ofits stroke in either direction to uncover the series of openings, asteam-cylinder at each end of and concentric with the pumpcylinder,steam-pistons connected with the pump-piston and movable in thesteam-cylinders, a valve-chest at the end of each steamcylinder, aslide-valve in each chest in axial alinement with the pistons, saidvalves being moved by movement of the pistons.

JOHN STUMPF.

In preseneeof- HENRY HAsPER, 'WOLDEMAR HAUPT.

